What: /sys/block//bcache/unregister Date: November 2010 Contact: Kent Overstreet Description: A write to this file causes the backing device or cache to be unregistered. If a backing device had dirty data in the cache, writeback mode is automatically disabled and all dirty data is flushed before the device is unregistered. Caches unregister all associated backing devices before unregistering themselves. What: /sys/block//bcache/clear_stats Date: November 2010 Contact: Kent Overstreet Description: Writing to this file resets all the statistics for the device. What: /sys/block//bcache/cache Date: November 2010 Contact: Kent Overstreet Description: For a backing device that has cache, a symlink to the bcache/ dir of that cache. What: /sys/block//bcache/cache_hits Date: November 2010 Contact: Kent Overstreet Description: For backing devices: integer number of full cache hits, counted per bio. A partial cache hit counts as a miss. What: /sys/block//bcache/cache_misses Date: November 2010 Contact: Kent Overstreet Description: For backing devices: integer number of cache misses. What: /sys/block//bcache/cache_hit_ratio Date: November 2010 Contact: Kent Overstreet Description: For backing devices: cache hits as a percentage. What: /sys/block//bcache/sequential_cutoff Date: November 2010 Contact: Kent Overstreet Description: For backing devices: Threshold past which sequential IO will skip the cache. Read and written as bytes in human readable units (i.e. echo 10M > sequntial_cutoff). What: /sys/block//bcache/bypassed Date: November 2010 Contact: Kent Overstreet Description: Sum of all reads and writes that have bypassed the cache (due to the sequential cutoff). Expressed as bytes in human readable units. What: /sys/block//bcache/writeback Date: November 2010 Contact: Kent Overstreet Description: For backing devices: When on, writeback caching is enabled and writes will be buffered in the cache. When off, caching is in writethrough mode; reads and writes will be added to the cache but no write buffering will take place. What: /sys/block//bcache/writeback_running Date: November 2010 Contact: Kent Overstreet Description: For backing devices: when off, dirty data will not be written from the cache to the backing device. The cache will still be used to buffer writes until it is mostly full, at which point writes transparently revert to writethrough mode. Intended only for benchmarking/testing. What: /sys/block//bcache/writeback_delay Date: November 2010 Contact: Kent Overstreet Description: For backing devices: In writeback mode, when dirty data is written to the cache and the cache held no dirty data for that backing device, writeback from cache to backing device starts after this delay, expressed as an integer number of seconds. What: /sys/block//bcache/writeback_percent Date: November 2010 Contact: Kent Overstreet Description: For backing devices: If nonzero, writeback from cache to backing device only takes place when more than this percentage of the cache is used, allowing more write coalescing to take place and reducing total number of writes sent to the backing device. Integer between 0 and 40. What: /sys/block//bcache/synchronous Date: November 2010 Contact: Kent Overstreet Description: For a cache, a boolean that allows synchronous mode to be switched on and off. In synchronous mode all writes are ordered such that the cache can reliably recover from unclean shutdown; if disabled bcache will not generally wait for writes to complete but if the cache is not shut down cleanly all data will be discarded from the cache. Should not be turned off with writeback caching enabled. What: /sys/block//bcache/discard Date: November 2010 Contact: Kent Overstreet Description: For a cache, a boolean allowing discard/TRIM to be turned off or back on if the device supports it. What: /sys/block//bcache/bucket_size Date: November 2010 Contact: Kent Overstreet Description: For a cache, bucket size in human readable units, as set at cache creation time; should match the erase block size of the SSD for optimal performance. What: /sys/block//bcache/nbuckets Date: November 2010 Contact: Kent Overstreet Description: For a cache, the number of usable buckets. What: /sys/block//bcache/tree_depth Date: November 2010 Contact: Kent Overstreet Description: For a cache, height of the btree excluding leaf nodes (i.e. a one node tree will have a depth of 0). What: /sys/block//bcache/btree_cache_size Date: November 2010 Contact: Kent Overstreet Description: Number of btree buckets/nodes that are currently cached in memory; cache dynamically grows and shrinks in response to memory pressure from the rest of the system. What: /sys/block//bcache/written Date: November 2010 Contact: Kent Overstreet Description: For a cache, total amount of data in human readable units written to the cache, excluding all metadata. What: /sys/block//bcache/btree_written Date: November 2010 Contact: Kent Overstreet Description: For a cache, sum of all btree writes in human readable units.